relocating batteries to engine compartment

Tin Lizzy · January 23, 2007, 07:20:38 AM

One of my 8D batteries has died so I think this is the time to relocate my batteries to engine compartment and use regular size batteries.

I know of others that have run the on/off switch and the battery cables back to engine compartment and I am not sure of the process. Is there a way to do this without keeping the extra cable in place?

Do I need regular vehicle batteries or do I need to get something heavy duty. All original air cond etc has been removed.

thanks
Harry

Buffalo SpaceShip · January 23, 2007, 07:42:33 AM

In moderate climates, you should be able to get by with (2) Grp.31s. As far as the actual relocation, I did it on my old 4106. Looks like you have an MCI based on the pic, but you might get some ideas on my page here: http://www.brownland.org/bus/batts/

The big concern is the routing of the big wires, at least #00s from the starter to the batts for a 24v starter. You'd need bigger wires like #0000 for a 12v system. Big + wire to starter solenoid, big - wire to starter or ground strap-engine block-firewall. There's also a big wire going to the alternator and usually a big one going forward to the blowers and/or old battery feed(s). Sometimes these are on bolts on the firewall and might not have to be disturbed.

I'd have new starter wires made up... should be less than $100 for #00s. Big electrical shops/ starter-rebuilt places can do this for you.

HTH,
Brian B.

TomC · January 23, 2007, 08:06:49 AM

The typical 8D starting battery is 1200cca (cold cranking amps). The most powerful size 31 is 1000cca. I have the 8V-71 in my bus and 2 turns it over just fine. If I need more juice, I can activate my jumper relay and kick in the deep cycle also (2-8D AGM).

Another way to go would be to use the 750cca size 31. Since they have smaller plates, typically have more room on the bottom of the battery case for sulfation-theoretically longer time to shorting out. But then you have to run 4 batteries with the 24v starter. Highly recommend changing from the 8D's to the 31's (155lb vs 80lbs ea). Virtually all big rig trucks use size 31's. Typically in warm climates, they can get by with 2 or 3 batteries. All sleeper trucks have four using the combo starting/deep cycle batteries. Also all big rigs are 12v. The only reason buses are 24v and use those huge 8D's is to support the AC fans when at idle. Granted the 8D's also have the most reserve power (length of cranking time), but with a decent engine (not worn out) and having the presence of mind to add fuel supplement if you're going to be in cold climate, the 2-31's will be enough-especially if you have a jumper relay like I do to allow the deep cycles to help also. Good Luck, TomC

DavidInWilmNC · January 23, 2007, 08:38:28 AM

Quote from: Tin Lizzy on January 23, 2007, 07:20:38 AM
One of my 8D batteries has died so I think this is the time to relocate my batteries to engine compartment and use regular size batteries.

I know of others that have run the on/off switch and the battery cables back to engine compartment and I am not sure of the process. Is there a way to do this without keeping the extra cable in place?

Do I need regular vehicle batteries or do I need to get something heavy duty. All original air cond etc has been removed.

thanks
Harry

I'm not sure what extra cable you're talking about. On my MC-8, there are three cables connecting to the master disconnect. You can remove the disconnect and tie those three cables together with an insulated post (similar to the one the grounds connect to, but insulated from the chassis). In the engince compartment, locate the post that connects the cable that runs up front to the starter and alternator. Mine's on a frame rail inside the right side engine door almost inboard from the tag wheels. This is the point where you'll want to connect your new batteries and master disconnect switch. You can reuse the positive cable from the battery to the switch, if it's in good shape, but you'll need one to go from that post to the switch. This way, you'll still have the switch where it can disconnect the batteries from everything. This is how I did it, but I didn't move my batteries to the engine compartment; I moved mine to the first bay with the other batteries and used the original battery compartment for the gas tank for the generator.

David

ChuckMC8 · January 23, 2007, 01:37:10 PM

Harry, (on MCI) I have pics of relocated batts and master disconnect switch on my foto page-

http://groups.msn.com/July2004Busphotos/shoebox.msnw?action=ShowPhoto&PhotoID=144

http://groups.msn.com/July2004Busphotos/shoebox.msnw?action=ShowPhoto&PhotoID=119

HTH, Chuck

Gary W · January 23, 2007, 03:23:48 PM

Hi Harry

When I had my MC-7, I relocated my starting batteries to the engine compartment. I used two group 31's and I put a disconnect switch back there. Worked great .

Gary

jjrbus · January 23, 2007, 05:18:36 PM

Gary, do not take out the existing battery cable right away. You may be able to utilize it later to tie your house batterys and bus batteries together.

Beatenbo · January 23, 2007, 06:15:11 PM

It was about 1968 GM went to 24v. Don't know about Prevost. Did Eagle go to 24v ?? don't know never owned an Eagle. Count how many buses have been built in the last 40 years. Why did they not change over to smaller batteries. No way I'd change 40 years of batteries. Do the mfgs not know what they are doing??

NJT5047 · January 23, 2007, 06:29:18 PM

Quote from: Gary W on January 23, 2007, 03:23:48 PM
Hi Harry
When I had my MC-7, I relocated my starting batteries to the engine compartment. I used two group 31's and I put a disconnect switch back there. Worked great .
Gary

I did the same. Two group 31s (John Deere tractor batteries) in the engine room on the old AC mount. I left all the OEM wiring in place and use it to charge the house batts, which are 2 8ds. Close the battery switch in the engine room and the engine will crank with the house batteries offline...close the original battery disconnect switch and the house batteries and cranking batteries are parallelled. With both closed, the engine alternator charges both crank and house batteries. There would seem to be an imbalance in battery sizes, but this setup has worked well without battery failure for going into the 4th season.
This system allows starting the bus on either the house, or crank batteries. Or one can isolate a problem battery bank if necessary.
As sez jjrbus, there's no reason to pull the OEM battery lead from the bus...it's useful if you wish to crank from the front batteries.
The capacity to parallel the batteries is useful....adds some redundancy.
When installing the new engine room batts and wiring, be sure that you use battery switches and wiring suitable for amp load your starter demands.
Two group 31s and a block heater will crank a good DD in any sort of weather...no block heater?

may have a problem. Then, you may have a problem with a pair of 8ds too...in cold weather!
JR

NJT5047 · January 23, 2007, 06:56:08 PM

Quote from: Beatenbo on January 23, 2007, 06:15:11 PM
It was about 1968 GM went to 24v. Don't know about Prevost. Did Eagle go to 24v ?? don't know never owned an Eagle. Count how many buses have been built in the last 40 years. Why did they not change over to smaller batteries. No way I'd change 40 years of batteries. Do the mfgs not know what they are doing??

Bus operators demanded huge OTR ACs. A bus with a functional OTR AC probably should retain the 8ds.
Without AC, the battery loads are similar to a truck...not especially demanding. Smaller batteries such as a pair of group 31s are adequate.
The AC is also the reason the large 50dn alternator is used on buses, but not on trucks.
Other than cold weather non-block heater cranking, 8ds are overkill.
I would seriously weigh losing the 50dn (I could change my mind

) if it failed. A 140 A automotive alternator would easily keep the bus batteries fully charged....sans OTR AC.
Now if you're using the bus alternator to operate a rooftop AC via an inverter for OTR AC, the 50dn becomes a bit more valued, as does a large house battery bank...sorta alters the equasion regarding downsizing alternators.
Still, cranking batteries are one subject, and house batts are another....
JR

Tom Y · January 23, 2007, 07:03:11 PM

Harry, I put mine back there. I took the MCI battery trays cut in half put about 3 inches in the middle. Now I can hold 3 group 31 batteries in each slide. Tom Y

DrivingMissLazy · January 23, 2007, 08:24:13 PM

At least in 1980 Eagle was 12 volt. I do not think they ever went to 24 volt.
Richard

Quote from: Beatenbo on January 23, 2007, 06:15:11 PM
It was about 1968 GM went to 24v. Don't know about Prevost. Did Eagle go to 24v ?? don't know never owned an Eagle. Count how many buses have been built in the last 40 years. Why did they not change over to smaller batteries. No way I'd change 40 years of batteries. Do the mfgs not know what they are doing??

Tony LEE · January 24, 2007, 08:59:48 PM

Give some thought to providing some shielding from radiant heat from the engine.

Tony

Dreamscape · January 25, 2007, 05:03:31 AM

That is why I am keeping mine where they were. In the original spot, driver side in front of the rear axle. I had thought about moving them back next to the starter, but I thought about heat from the engine. I also thought about enclosing them, but decided not to interfere with air movement to help cool the beast down. Whether I am right or wrong, I made the choice. It might work for you.
Do it your way and give it a whirl.

Happy Trails,

Paul

Dreamscape

Stan · January 25, 2007, 05:36:10 AM

Heat is not good for batteries, but almost all cars have the battery under the hood where the temperature is much higher than the engine comparment of a bus. If you get threee years of use out of starting batteries, you are pushing your luck after that. Both batteries and tires should be replaced before they fail. They are a maintenance item like oil and filters.